The present invention is in the field of catalysis and specifically relates to improved oxide catalyst support materials of high surface area useful for supporting oxidation catalysts at elevated temperatures.
In general, catalyst support materials for gas-phase oxidation reactions should exhibit high surface area, refractoriness, and inertness toward the supported catalyst at high temperatures. High surface area in the support can increase the surface area of the supported catalyst or, at low catalyst loadings, insure a high degree of catalyst dispersion which retards activity loss resulting from catalyst agglomeration and sintering.
Gas phase oxidation reactions may involve elevated temperatures, e.g., ranging up to 800.degree.C. or more, and a catalyst support material for this use should exhibit sufficient refractoriness to be useful at these temperatures. In particular, the catalyst support material should resist sintering and retain high surface area despite prolonged exposure to such temperatures.
The severe conditions which often accompany catalytic gas phase oxidation processes accelerate interactions between the supporting material and the catalyst, typically resulting in loss of activity. Therefore, the selected catalyst support should be highly inert with respect to the supported catalyst at the temperatures of use.
A wide variety of refractory metal oxides and metal oxide mixtures have been utilized to support noble metal and base metal oxide oxidation catalysts, including alumina, silica, magnesia, titania, zirconia, and mixtures thereof. However, some of these, such as alumina, are reactive with respect to base metal oxide catalysts such as copper chromite and cobalt oxide under the conditions encountered in high temperature oxidation reactions. Also, many exhibit substantially reduced surface areas following exposure to temperatures in the 800.degree.C. range.